World War II poster from the United States on the United Nations. (U.S. National Archives and Records Administration/Wikimedia Commons)
The Allied vs. Axis Powers
Due to the bombing of Pearl Harbor in December 1941, the United States joined World War II as part of the Allied Powers, and the Atlantic Charter was formalized between the U.S., the Soviet Union, the United Kingdom, and China in January 1942. Along with 22 other nations, they agreed to work together against the Axis Powers of Italy, Germany, and Japan with the eventual goal of a permanent system of general security for the whole world. This was a giant leap toward defeating oppression across the globe.
The next and final step would not happen for another three years. The sudden death of President Roosevelt on April 12, 1945 meant he never saw his plans reach fruition, but President Truman moved forward with the arrangements, and the United Nations Conference on International Organization commenced in San Francisco as scheduled on April 25. After working for two months, the 50 nations represented at the conference signed the Charter of the United Nations, though many of them needed approval from their congresses or parliaments before the United Nations could be formally established.